The present invention finds application particularly in next generation networks as defined by 3GPP and which is commonly known as Long Term Evolution (LTE). However, the techniques may be applicable also in connection with other types of radio networks, such as WCDMA, GSM, CDMA etc. Thus, may for instance Radio Base Station (RBS) as used hereinafter refer to eNodeB (eNB) in LTE as well as NodeB (NB) in WCDMA or any other node handling a radio interface in a radio network.
The radio network equipment vendors choose in the product implementation, in cooperation with the operator, which Radio Link Control (RLC) Mode to use for a certain radio bearer with a certain Quality of Service Class Identifier (QCI). With the low round trip time in LTE, different RLC Modes may be suitable for real-time services. Therefore, it can be foreseen that some vendors select unacknowledged RLC for real-time services like Voice over Internet Protocol (VoIP), while others select acknowledged RLC.
According to the 3GPP standard reconfiguration of RLC Mode of data radio bearers (DRBs) is not supported in E-UTRAN, making the radio bearer being dropped during handover if there is a mismatch in RLC Mode between Source eNB and Target eNB for a certain radio bearer with a certain QCI.